Patent GB-953838-A (GB)
Title: Improvements in or relating to apparatus for forming screwthreads
IPC: B23G5/12
Filed: 1963-02-15
Abstract: 953,838. Rolling screw threads; screwing. ROBERT BOSCH G.m.b.H. Feb. 15, 1963 [Feb. 16, 1962; Oct. 15, 1962], No. 6172/63. Headings B3M and B3N. Apparatus for screwing comprises an automatically openable die head having a member coupled to the drive and rotatable relative thereto against the force of a spring, jaws in the die which are closed when the member is coupled to the drive, and opened when uncoupled, and a tensioning device for holding a workpiece non-rotatably mounted on the apparatus for axial displacement relative to the die head, the die head, its drive, and the tensioning device being combined to form a portable hand tool. Die head 1, Fig. 1, is driven by an electric motor 4 through a gear train 5, and is located in a housing 12. A ring 24, Figs. 1, 3, is mounted on a sleeve 23, and can be rotated against a spring 25. Four screwing jaws 27 are radially guided by cams 26 on ring 24, and saw teeth 28 are provided on the latter. A driving flange 6 is adjustably clamped on sleeve 23, and an indicator 112, Fig. 5, carried by the sleeve moves over a scale 113 on flange 6 during such adjustment. A bolt 32, having pins 83, 84, is axially displaceable, and rotatable in flange 6, and can be brought into engagement with a recess 33 in ring 24, means 91 being provided for causing axial displacement, and means 92 being provided for causing rotation of the bolt. The tensioning device 3 comprises an arm 8 and a control disc 9 and is guided for axial displacements on two sleeves 18 carried by screws 14. Arm 8 carries pivoting work clamping jaws 59 and disc 9 is provided with a hood 62 and a plate 66 having three radial slots 67 which cooperate with pins 60 on jaws 59. Rotation of disc 9-in the direction of arrow 105, Fig. 3, by means of a handle 11 opens jaws 59. Handle 11 can be swung through 90 degrees so that in one position a stop 77 is in engagement with teeth 28 of ring 24, and in the other position it is in engagement with disc 9. In operation jaws 27 are closed by swinging handle 11 into the position of Fig. 1, and then turning the handle together with disc 9 and ring 24, in the direction of arrow 106, Fig. 3. Bolt 32 snaps into recess 33 thus preventing relative movement of parts 6 and 24. Handle 11 and disc 9 are now rotated in the direction of arrow 105 so that stop 77 slides over teeth 28 and jaws 59 of arm 8 are opened. Workpiece 73 is inserted into device 3 until it is stopped by jaws 27, handle 11 is swung through 90 degrees, is rotated together with disc 9 in the direction of arrow 106 thus closing jaws 59 on to the work. Switch 48 is pressed and the die head 1 rotates to produce an external thread on the workpiece. Device 3 is moved towards the die head by the work against the force of springs 51 until it engages an adjustment screw 53 which urges a switch 93 into engagement with a disc 88 carried by bolt 32 thus moving the latter out of recess 33 and jaws 27 are opened by spring 25. If it is desired to interrupt the cutting process, switch 93 can be operated by hand, and bolt 32 can be rotated into two positions by means 92 so that the depth of cut can be varied.